Tutorial #3: How to bend tubing.

15May09

As with any complex task, the key lies in preparation. For this task, you will need:

1 length of tubing
fine sand, or salt
small piece of scrap metal
solder
soldering torch
soldering block
blu-tack, sticky tape, glue or wax
mandrel or triblet

INSTRUCTIONS

1. Flux tube thoroughly. This reduces the appearance of firescale.

2. Solder one end closed with a piece of scrap sheet silver and allow to cool, or quench.

Tube, sealed

3. Anneal tube to cherry red and allow to cool. Quenching will harden the metal slightly and at this point that isn’t what you want.

4. Fill tube with clean fine sand. Salt or sugar will also do, cornmeal at a pinch.

Tube filled with sand

5. Seal other end of the tube – blu-tack, wax, glue, sticky tape. If you try to solder it shut the heat from the torch will make the air between the grains of sand expand and it shoots out the end – nice patterns, but a messy workbench and loose sand in the tube = kinked bend.

Tube, blu-tacked

Tube, taped up

6. Bend the tube around a former. This can be a mandrel, a triblet or even a pencil depending on the thickness of your tubing and the diameter of the required curve.

Tube, large bend

Tube, small bend

Tube, one coil

Tube, two coils

Tube, three coils

7. Unseal the end, pour out the sand and reserve for other projects. Use the bent tubing in projects.

TOP TIPS FOR HAPPY TUBE-BENDING

1. Use more tube than you need, because the ends don’t bend so well without force and tend to come out distorted or dented if you mallet them. You also need somewhere to grip the tube, at least until the first full curve.

2. Know the curve you want, beacuse changing it later is difficult. If you want to change the tightness of the curve after you’ve poured out the sand, you’ll have to refill it and seal it up again.

4. Make sure the sand is packed well in by tapping the end of the tube to make it settle. The aim is to fill as much of the void in the tubing so it behaves like a solid.

5. Understand a little about the pressures of expansion and compression within the metal as it curves. Metal WILL break under strain and there is no internal strength in the core of the tubing, even when it’s packed with sand. Annealling the tube means you don’t have to force it, so there’s less chance of it collapsing.

6. If you quench the tube after annealling it, make sure it’s dry all the way down to the end inside because the sand will stick to the inside wet walls of the tube and clump up, causing gaps in the filling, thus causing the tube to kink when you bend it.

7. If you want to add a hammered texture to the tube, do this before you pour out the sand. It’s easier, and less likely to crush the tube.

Happy bending!

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Filed under: Jewellery, how to, silversmithing   |  3 Comments
Tags: handmade, help, how to, jewelry, metalsmith, silver, silversmith, silversmithing, tubular belle, tutorial, uk